Subdivide ResourceRecord types

src/IPMeow.Dns/DnsMessage.cs

@@ -22,7 +22,7 @@ public struct DnsMessage : IBinarySerializable<DnsMessage>
     public DnsMessageType MessageType { get; set; }
     public DnsMessageOpcode Opcode { get; set; }
     public DnsResponseCode ResponseCode { get; set; }
-    public ICollection<ResourceRecord> Questions { get; set; }
+    public ICollection<QueryResourceRecord> Questions { get; set; }
 
     public static DnsMessage Deserialize(ReadOnlyMemory<byte> data)
     {

src/IPMeow.Dns/ResourceRecord.cs

@@ -51,17 +51,44 @@ public enum ResourceRecordClass : short
     HS = 4,
 }
 
-public struct ResourceRecord : IBinarySerializable<ResourceRecord>
+public record QueryResourceRecord : IBinarySerializable<QueryResourceRecord>
 {
-    public string Name { get; set; }
+    public bool IsQuery => true;
+    public string Name { get; set; } = default!;
+    public int Labels => Name.Split('.').Length;
+    //UTF8
+    internal int NameOffset => Name.Split('.').Select(x => x.Length).Sum() + Labels + 1;
     public ResourceRecordType Type { get; set; }
     public ResourceRecordClass Class { get; set; }
-    public TimeSpan Ttl { get; set; }
 
 
-    public static ResourceRecord Deserialize(ReadOnlyMemory<byte> data)
+    public static string DeserializeName(BitEnumerator b)
     {
-        throw new NotImplementedException();
+        StringBuilder sb = new();
+        byte len;
+        while ((len = b.TakeByte()) != 0)
+        {
+            sb.Append(Encoding.UTF8.GetString(b.TakeBytes(len))).Append('.');
+        }
+
+        return sb.ToString().Trim('.');
+    }
+
+    public static QueryResourceRecord Deserialize(ReadOnlyMemory<byte> data)
+    {
+        BitEnumerator b = new(data);
+        string name = DeserializeName(b);
+
+        ResourceRecordType type = (ResourceRecordType)b.TakeInt16();
+        ResourceRecordClass clazz = (ResourceRecordClass)b.TakeInt16();
+
+
+        return new QueryResourceRecord()
+        {
+            Name = name,
+            Class = clazz,
+            Type = type,
+        };
     }
 
     public ReadOnlySpan<byte> SerializeName()
@@ -73,7 +100,7 @@ public struct ResourceRecord : IBinarySerializable<ResourceRecord>
             throw new ArgumentOutOfRangeException("Name must be less than 255");
         }
 
-        ArrayBufferWriter<byte> buffer = new(name.Length + 1 + 4);
+        ArrayBufferWriter<byte> buffer = new(NameOffset);
 
         foreach (string s in name.Split('.'))
         {
@@ -90,7 +117,7 @@ public struct ResourceRecord : IBinarySerializable<ResourceRecord>
         return buffer.WrittenSpan;
     }
 
-    public ReadOnlyMemory<byte> Serialize()
+    public virtual ReadOnlyMemory<byte> Serialize()
     {
         var buffer = new ArrayBufferWriter<byte>();
 
@@ -99,11 +126,53 @@ public struct ResourceRecord : IBinarySerializable<ResourceRecord>
         buffer.Advance(2);
         BinaryPrimitives.WriteInt16BigEndian(buffer.GetSpan(), (short)Class);
         buffer.Advance(2);
-        BinaryPrimitives.WriteInt32BigEndian(buffer.GetSpan(), (int)Ttl.TotalSeconds);
-        buffer.Advance(4);
-        //TODO: Implement RDATA
-        BinaryPrimitives.WriteInt16BigEndian(buffer.GetSpan(), 0);
-        buffer.Advance(2);
+
+        return buffer.WrittenMemory;
+    }
+}
+
+public record ResourceRecord : QueryResourceRecord, IBinarySerializable<ResourceRecord>
+{
+    public TimeSpan Ttl { get; set; }
+    public byte[] Data { get; set; } = Array.Empty<byte>();
+
+    static ResourceRecord IBinarySerializable<ResourceRecord>.Deserialize(ReadOnlyMemory<byte> data)
+    {
+        QueryResourceRecord qr = Deserialize(data);
+        BitEnumerator b = new(data);
+        b.Skip(qr.NameOffset);
+
+        TimeSpan ttl = TimeSpan.FromSeconds(b.TakeInt32());
+        short dataLen = b.TakeInt16();
+        byte[] rdata = b.TakeBytes(dataLen);
+
+        return new ResourceRecord()
+        {
+            Name = qr.Name,
+            Class = qr.Class,
+            Type = qr.Type,
+            Ttl = ttl,
+            Data = rdata
+        };
+    }
+
+    public override ReadOnlyMemory<byte> Serialize()
+    {
+        var buffer = new ArrayBufferWriter<byte>();
+        buffer.Write(base.Serialize().Span);
+
+        BinaryPrimitives.WriteInt32BigEndian(buffer.GetSpan(), (int)Ttl.TotalSeconds);
+        buffer.Advance(4);
+
+        //TODO: Implement RDATA
+        BinaryPrimitives.WriteInt16BigEndian(buffer.GetSpan(), (short)Data.Length);
+        buffer.Advance(2);
+
+        if (Data.Length > 0)
+        {
+            buffer.Write(Data);
+        }
+
         return buffer.WrittenMemory;
     }
 }

src/IPMeow.Lib/BitEnumerator.cs

@@ -26,6 +26,11 @@ public class BitEnumerator
         return data.ToArray();
     }
 
+    public void Skip(int len)
+    {
+        _position += len;
+    }
+
     public short TakeInt16()
     {
         short num = BinaryPrimitives.ReadInt16BigEndian(_data.Span[_position..(_position + 2)]);

test/IPMeow.Test/DnsTest.cs

@@ -20,12 +20,11 @@ public class DnsTest
             MessageId = 0xbabe,
             MessageType = DnsMessageType.Query,
             Opcode = DnsMessageOpcode.Query,
-            Questions = new List<ResourceRecord>()
+            Questions = new List<QueryResourceRecord>()
             {
-                new ResourceRecord()
+                new QueryResourceRecord()
                 {
                     Class = ResourceRecordClass.IN,
-                    Ttl = TimeSpan.Zero,
                     Name = "meow.lgbt",
                     Type = ResourceRecordType.A
                 },
@@ -37,7 +36,7 @@ public class DnsTest
         Console.WriteLine("sendt");
 
         msg.IsRecursionDesired = false;
-        msg.IsAuthoritative = true;
+        msg.IsAuthoritative = false;
         msg.MessageType = DnsMessageType.Reply;
         msg.Opcode = DnsMessageOpcode.Status;
         msg.ResponseCode = DnsResponseCode.NxDomain;